Discovery News reports:
Based on charred remains of plant material found at hot rock oven
sites [across North America], cooked versions of [a] root vegetable [called the camas bulb] -- somewhat like a cross
between an onion and a potato -- is thought to have been the tortilla
of the Stone Age.
The bulbs required up to two days to bake, due to a complex carbohydrate called inulin that is otherwise indigestible.
Alston Thoms, who conducted [two] studies [on the rock ovens], told Discovery News that
"camas consumption preceded corn consumption everywhere in the U.S. by
thousands of years."
Wikipedia elaborates:
The Quamash was a food source for quite a number of native peoples
in the western United States and Canada. After being harvested in the
autumn, once the flowers have withered, the bulbs were pit-roasted or boiled. A pit cooked camas bulb looks and tastes something like baked sweet potato, but sweeter, and with more crystalline fibers due to the presence of inulin in the bulbs. When dried, the bulbs could be pounded into flour. Native American tribes who ate camas include the Nez Perce, Cree, Coast Salish, Lummi, and Blackfoot tribes, among many others. Camas bulbs contributed to the survival of members of the expedition of Lewis and Clark (1804-1806).
Though the once-immense spreads of camas lands have diminished because of modern developments and agriculture, numerous Camas prairies and marshes may still be seen today.
Warning: While Camassia species are edible and nutritious, the white-flowered Deathcamas species (which are not the genus Camassia, but part of the genus Zigadenus)
that grow in the same areas are toxic, and the bulbs are quite similar.
It is easiest to tell the plants apart when they are in flower.